The present invention relates generally to the field of alternators as used, for example, to supply DC electrical power to motor vehicles and, more particularly, to an improved alternator rectifier bridge assembly provided within an alternator housing and a method of making the bridge assembly
A three phase alternator rectifier bridge, such as used in a motor vehicle alternator, comprises three "negative" diodes having their anodes connected to a ground terminal and three "positive" diodes having their cathodes connected to a voltage output terminal. Each of the cathodes of the negative diodes are connected to one of the anodes of the three positive diodes and to one of three stator windings of an alternator. In the interest of conserving space and facilitating the manufacture and repair of alternators, the diodes used to form rectifier bridge circuits have been packaged together as a unit which preferably is mounted within the housing of the alternator. For example, U.S. Pat. No. 3,184,625 describes a technique for mounting diodes on metal plates within the housing of an alternator. The metal plates are shown to provide electrical interconnection to common terminals for each set of diodes. However, numerous wire-to-wire solder connections are required to interconnect the diodes in the rectifier unit.
Such compact packaging also creates a problem commonly addressed in known prior art rectifier bridge circuits, i.e. the dissipation of heat which is generated by the conduction of substantial currents through the diodes of the bridge circuits. U.S. Pat. Nos. 3,539,850, 3,925,809, 3,959,676, 4,218,694, 4,307,437, 4,321,664, 4,538,169, 4,799,309 and 4,835,427 all show various techniques for packaging diodes in a manner that will facilitate heat dissipation. In particular, U.S. Pat. No. 3,959,676 describes sandwiching the diodes between a pair of heat sinking DC terminal plate members and a generally U-shaped circuit board member comprised of conductive strips embedded within and insulated by a plastic material The resulting unitary composite body is mounted within the housing end plate of an alternator. U.S. Pat. No. 4,538,169 describes another sandwiched diode structure wherein a base is mounted on the alternator housing case to transfer heat directly thereto.
While the known rectifier bridge circuit arrangements perform satisfactory heat transfer/dissipation, further improvements in heat transfer/dissipation and simplification of the structure of bridge circuit arrangements are always in demand to further the state of the art and, more importantly in view of the competitive nature of the motor vehicle industry, to provide lower costs through simplified assembly with parts which are less expensive and fewer in number.